Preparation and Photoluminescence of Partially Filled ZnO Microtubes Using Block Copolymers

Partially filled ZnO microtubes were synthesized in large scale using block copolymers. The growth mechanism of this unique construction is proposed on the basis of adsorption of block copolymers on {0002} plane of wurtzite ZnO. The photoluminescence property of these unique ZnO microtubes is also studied using a Xe lamp as the excitation source at room temperature. Blue emission band at 425 nm is a much stronger ultraviolet emission band, which is due to laminar structure of ZnO microtubes.     

Effects of ion group content and polyol molecular weight on physical properties of HTPB‐based waterborne poly(urethane‐urea)s

A series of waterborne poly(urethane‐urea)s, WPUUs, based on using nonpolar hydroxyl‐terminated polybutadiene (HTPB) as the soft segment, were successfully synthesized in this article. The effects of the COOH group content and soft‐segment molecular weight (Mn_s) on the dispersion, morphology, and physical properties were investigated. Variations of the particle size, viscosity, and zeta potential were first governed by the hydrophilicity of the polymer chain, and then by the swelling derived from water. Fourier transfer infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) indicated that the degree of phase separation decreased as the COOH group content increased or as Mn_s decreased. However, the hydrogen bonding between the soft and hard segments and the two‐phase mixing could not occur in this nonpolar HTPB‐based WPUU system, indicating that the hard segments tended to form smaller domains and to pack more loosely. It was attributed to the fact that the presence of bulky ionic salt groups destroyed the ordered arrangement of the hard segments. In this case, the increases of the interface area between the soft and hard phases resulted in that the present behaviors were similar to the phase mixing. In tensile properties, HTPB‐based WPUUs exhibited higher tensile stress, elongation at break, and modulus as the COOH group content decreased or as Mn_s decreased. In thermal degradation, the introduction of HTPB polyol improved the thermal stability of WPUU. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

炭黑填充硬聚氯乙烯的改性

为使聚氯乙烯具有抗静电性能,采用加入具有导电性填料的方法,但加入大量的填料,会使硬聚氯乙烯的冲击性能降低,加工性能变差。本文是在以炭黑为填料的基础上,研究不同的改性剂和加工助剂改进硬聚氯乙烯的效果,结果表明,加入冲击改性剂和加工助剂后,大大增加了硬聚氯乙烯的冲击强度,且加工性能也得到改善,同时由于炭黑具有补强效果,其拉伸强度和弯曲强度在加入改性剂后也能满足使用要求。     

新型陶瓷刀具材料的研究与开发

工业用钢材的质量提高使材料加工难度增加,耐高温的高硬度高强度陶瓷材料被用做切削刀具并逐渐推广应用。本文对陶瓷刀具的材质、种类、性能特点作了比较和评价,并重点介绍了新型的晶须增韧陶瓷刀具。最后,对陶瓷刀具的市场前景进行了预测,并指出了陶瓷刀具研制方面应该深入研究的课题。     

Diamond growth by carbon ion implantation of diamond

Medium energy (5–25 keV) ¹³C⁺ ion implantation into diamond (100) to a fluence ranging from 10¹⁶ cm⁻² to 10¹⁸ cm⁻² was performed for the study of diamond growth via the approach of ion beam implantation. The samples were characterized with Rutherford backscattering/channelling spectroscopy, Raman spectroscopy, X-ray photoemission spectroscopy and Auger electron spectroscopy. Extended defects are formed in the cascade collision volume during bombardment at high temperatures. Carbon incorporation indeed induces a volume growth but the diamond (100) samples receiving a fluence of 4 × 10¹⁷ to 2 × 10¹⁸ at. cm⁻² (with a dose rate of 5 × 10¹⁵ at. cm⁻² s⁻¹ at 5 to 25 keV and 800 °C) showed no He-ion channelling. Common to these samples is that the top surface layer of a few nanometers has a substantial amount of graphite which can be removed by chemical etching. The rest of the grown layer is polycrystalline diamond with a very high density of extended defects.     

Kinetics for benzoylation of sodium 4-acetylphenoxide via third-liquid phase in the phase-transfer catalysis

In this research, the kinetics for synthesizing 4-acetylphenyl benzoate (R^*COOR) from benzoylation of sodium 4-acetylphenoxide via third-liquid phase-transfer catalysis was investigated. The reaction rate was observed to be strongly dependent on agitation speeds in the third-phase catalytic reaction. By forming the third-liquid phase, the observed reaction can be greatly enhanced to give a product yield of 100% in a duration of 3 min at 20 °C and 200 rpm. If a third-liquid phase was not formed in the liquid–liquid system, the reaction rate is very slow and the product yield is only 2% in 3 min at 20 °C. The reaction conducted in third-liquid phase-transfer catalytic system is faster than that in LLPTC system by 25–28 times. The amount of catalytic intermediate (QOR) in the third-liquid phase was about 50% of the catalyst initially added and kept about 30% of it remained after 1 min, and only small amounts of a catalytic intermediate residing in the organic phase were observed during the reaction using methyl t-butyl ether as the solvent. The concentration of catalytic intermediate slightly decreased with increasing reaction time, while the molar ratio of QOR to benzyl tri-n-butylammonium cation in the third-liquid phase remained almost constant after 1 min and increased with increasing agitation speeds. The experimental results were well described by the pseudo-first-order kinetics. The present work shows an effective method to synthesize 4-acetylphenyl benzoate.     

碳化硅陶瓷的性能与应用

详细的介绍了碳化硅原料的生产，碳化硅陶瓷的抗氧化、耐酸碱等化学性能，微观结构、色泽、热膨胀和导热系数、硬度、韧性等物理性能。并阐述了3种常用碳化硅陶瓷的致密化技术以及碳化硅在耐火材料、军事、航空航天、钢铁、电气和电工等工业部门的应用以及优越的性能和未来的应用前景。     

Feature-Adaptive Rendering of Loop Subdivision Surfaces on Modern GPUs

We present a novel approach for real-time rendering Loop subdivision surfaces on modern graphics hardware. Our algorithm evaluates both positions and normals accurately, thus providing the true Loop subdivision surface. The core idea is to recursively refine irregular patches using a GPU compute kernel. All generated regular patches are then directly evaluated and rendered using tile hardware tessellation unit. Our approach handles triangular control meshes of arbitrary topologies and incorporates common subdivision surface features such as semi-sharp creases and hierarchical edits. While surface rendering is accurate up to machine precision, we also enforce a consistent bitwise evaluation of positions and normals at patch boundaries. This is particularly useful in the context of displacement mapping which strictly requires inatching surface normals. Furthermore, we incorporate efficient level-of-detail rendering where subdivision depth and tessellation density can be adjusted on-the-fly. Overall, our algorithm provides high-quality results at real-time frame rates, thus being ideally suited to interactive rendering applications such as video games or authoring tools.     

Exploring the Interactions of Storylines from Informative News Events

Today＇s news readers can be easily overwhelmed by the numerous news articles online. To cope with information overload, online news media publishes timelines for continuously developing news topics. However, the timeline summary does not show the relationship of storylines, and is not intuitive for readers to comprehend the development of a complex news topic. In this paper, we study a novel problem of exploring the interactions of storylines in a news topic. An interaction of two storylines is signified by informative news events that play a key role in both storylines. Storyline interactions can indicate key phases of a news topic, and reveal the latent connections among various aspects of the story. We address the coherence between news articles which is not considered in traditional similarity-based methods, and discover salient storyline interactions to form a clear, global picture of the news topic. User preference can be naturally integrated into our method to generate query-specific results. Comprehensive experiments on ten news topics show the effectiveness of our method over alternative approaches.